Brown pelicans and the oil spill

Oil-covered brown pelicans

As of November 2009, Louisiana’s state bird, the brown pelican, was not an endangered species. The pelican population had dropped to a low of 10,000 birds in 1970, mostly due to the use of pesticides like DDT that weakened the eggshells so that they couldn’t support the embryos to maturity. But when the numbers rose to an estimated 650,000 birds last year, they were taken off the endangered species list. This was a conservation success story of the type that we rarely hear.

Now, in the aftermath of the Gulf oil spill, the web is flooded with pictures of oil-logged brown pelicans, and conservationists fear that all their hard work will be wiped away by this one catastrophic event. One of the pelicans’ main nesting grounds is the Breton National Wildlife Refuge on the Chandeleur Islands off the coast of Louisiana (click the link for an interactive map of the impacted area). Oil has hit the refuge hard, turning the once green and thriving marshland brown and gunky and lending an air of uncertainty to the pelicans’ future.

The oil spill presents a number of dangers, including habitat destruction and food chain disruption, not to mention the toxicity associated with ingestion of the oil. The many toxic hydrocarbons in the oil can wreak havoc on a bird’s liver, brain, nervous system, and other systems if the birds ingest oil or absorb it through their skin, in some cases leading to death. Oil-coated birds are also in danger of hypothermia; they depend on their feathers to trap a layer of air that acts as insulation meant to keep them warm and dry. Oil disrupts the feather structure, rendering the birds defenseless against the elements, and in some cases they become so preoccupied with the need to clean themselves that they starve to death while obsessively preening. Their eggs are also very vulnerable to oil; although the shells are hard, they are also porous, and eggs exposed to oil can absorb the toxic chemicals. Just one drop of oil can be enough to spell doom for these delicate embryos.

It’s not yet known how the spill will really affect the brown pelican population. It’s possible that the oil won’t make it to the refuge interior, but at this point it seems unlikely that much of this wetland area will remain unscathed. The brown pelican will have a new challenge to face in the months and years ahead.

Further reading:
Scientific American
New York Times